He won in the story competition and his parents were very .
A:smart
B:proud
C:sorry
D:upset
在二次函数y=ax2+bx+c的图象如图所示,下列说法中:①b2﹣4ac<0;②-b2a>0;③abc>0;④a﹣b﹣c>0,说法正确的是____ (填序号).